Catheters are, essentially, elongated flexible narrow-bore tubes used to gain access to body organs from the exterior of the body, through the body's natural ducts. They may be inserted, for example, through a patient's urethra to enter the bladder, to drain fluids therefrom or to deliver fluids thereto. They may be inserted into a major artery, and fed through the artery a considerable distance, e.g. to the vicinity of the heart. Instead of being used for the delivery or collection of fluids, they may be equipped with medical devices so that a specific medical procedure can be performed at a particular location of the artery, such as an angioplasty to relieve an occluded or partially occluded artery.
Accordingly, catheters have a number of very demanding technical criteria to meet. They must be flexible enough and thin enough to accommodate the contours of the body duct, without causing internal damage. They must provide reliable fluid communication over substantial distances. They must exhibit a high degree of biocompatibility. Their distal ends must be equipped with appropriate apparatus to perform their intended function. Commonly, such apparatus must be arranged so as to be operable from outside the patient's body, after insertion of the catheter to its correct location.
There are instances where, for critical therapeutic purposes, it is necessary to inject a patient's myocardium with a therapeutic fluid, such as a DNA solution, in very small amounts and at a precise location. The myocardium is the middle, cardiac muscle portion of the heart wall, surrounding the heart chambers. It is the thickest part of the heart wall, having a maximum thickness, in the ventricle walls, of about 2.5 cm. Blood vessels permeate the myocardium. The capillary beds therein are so extensive that more oxygen is released in the myocardium by the circulating blood than in any other organ of the body. Localized treatment of the myocardium to treat muscular damage thereto, e.g. with therapeutic substances, is sometimes needed. Very precise control over the location and delivery of such therapeutic substances is accordingly necessary. Very small amounts of very expensive therapeutic substances such as up to 0.05 ml of DNA solution are often required to be delivered, with precise control over location and quantity.
It is an object of the present invention to provide a novel catheter for fluid delivery to internal organs of a mammalian body.
It is a further object of the invention to provide a catheter specifically adapted for delivering fluids to the myocardium.